The invention pertains to a method for producing a strand or cable, in which fibers and/or wires are twisted at a cabling point to form the strand or cable. The invention also pertains to a device for carrying out the method and to a cable which can be produced by the method.
Such methods by means of which wire strands or cables are produced from natural fibers, plastic fibers, or wires are known from a history of use and are usually carried out with a cabling machine. Spools onto which the fiber strands or wires to be cabled are wound are arranged on the rotor of the cabling machine. The fiber strands or wires are guided under rotation to the cabling point, where they are twisted to form the strand or cable, and the formed strand or cable is then wound up onto a cable drum.
Such methods are also used in particular to produce strands and cables which comprise high-strength plastic fibers of aramid, for example. Such strands and cables are very strong for their weight and volume.
For this reason, plastic fiber cables are used in mountain climbing to ensure the safety of the climbers. The advantage of such plastic fibers is also manifest when they are used in wire cables of considerable length for use in suspended applications, e.g., for hoist cables in mining or for deep-sea cables. In applications such as this, the weight of the wire cable itself uses up a large percentage of the load-bearing capacity of the cable; the useful load is reduced to a corresponding extent.
The problem with plastic fibers is that, although they are very strong in the longitudinal direction, they are quite weak in the transverse direction, and there is therefore a considerable danger of breakage under certain types of load.
The plastic fiber cables used to ensure the safety of mountain climbers normally comprise a core-jacket structure, in which the core consists of fiber strands which have been twisted together. The cabled fiber strands are protected from damage by a jacket, which is braided around them and which thus holds them together.
The method indicated above is also used to produce composite cables in which the core cable consists of high-strength plastic fibers and the external strands consist of steel wire. For example, in the case of the cable known from U.S. Pat. No. 6,563,054 B1, a jacket of thermoplastic material is applied around a core cable of parallel plastic fibers, and the steel wire strands are cabled on top of that.